Like most EVs, the Ioniq Electric still runs a small 12V lead-acid battery alongside the main traction pack, quietly keeping the low-voltage systems alive. Mine finally gave up, so a replacement was overdue.
The swap itself was straightforward, but reconnecting it threw up a couple of quirks I wasn’t expecting. Regenerative braking reset back to its default level, rather than remembering the setting I’d left it on. Not a big deal, just a case of dialling it back in from the paddle shifters.
More oddly, the welcome light stopped working after the reconnect. A bit of digging suggests this is a fairly common side effect of disconnecting the 12V supply, and it’s usually just a case of letting the car’s various modules re-initialise properly over a few drive cycles.
Worth keeping an eye on the 12V battery health generally. It’s a small, cheap part, but a flat one can strand a car that’s otherwise got 200 miles of range sat in the main battery.